1. Field of the Invention
The present invention relates to a portable telephone terminal, and specifically relates to a portable information terminal such as a portable telephone terminal, portable gaming device, or palm-size personal computer which can be altered between a portable state and usable state.
2. Description of the Related Art
Portable information terminals which are represented by a portable telephone terminal or the like are being developed in various forms so as to be more compact in a portable state than in a usable state. Representative forms thereof include a so-called “shell-form” (flip-phone) which employs a configuration which opens and closes similar to that of a clam-shell, and a “sliding form” wherein an upper casing slides as to a lower casing.
The technology described in Japanese Unexamined Patent Application Publication No. 2006-93999 is exemplified in FIG. 13 as an example of a sliding-type portable telephone, i.e. a sliding-type portable telephone which is formed with an upper casing 1 having a display unit 3 and receiver 4, and a lower casing 2 having an operating unit 5 and transmitter 6, so as to be slidable.
As shown in FIG. 13A, in the state of the upper casing 1 and lower casing 2 being closed, the display unit 3 and receiver 4 of the upper casing 1 are exposed, whereby the operating unit 5 and transmitter 6 of the lower casing 2 are covered by the upper casing 1. Also, as shown in FIG. 13B, in the state that the upper casing 1 and lower casing 2 are opened, the state thereof is such that each of the display unit 3 and receiver 4 of the upper casing 1 and the operating unit 5 and transmitter 6 of the lower casing 2 are exposed.
As shown in FIG. 13B, the dimensions in the sliding direction are L1 for the upper casing 1 and L2 for the lower casing 2, the dimensions in the state of the upper casing 1 and lower casing 2 being opened is L3, which is a dimension whereby a dimension L4 of the overlapped portion is subtracted from the sum total of L1 and L2.